The invention pertains to methods of forming nitrogen-containing masses and silicon nitride layers. The invention also pertains to methods of forming capacitor constructions.
Silicon nitride is commonly utilized as an insulative material during semiconductor device fabrication. For instance, silicon nitride can be utilized as a dielectric material in capacitor constructions. Another use for silicon nitride in semiconductor device fabrication is as a barrier layer to impede migration of, for example, oxygen, hydrogen, and metallic materials.
It can be desired to simultaneously deposit silicon nitride over a conductively-doped silicon material and a silicon oxide. For instance, it can be desired to deposit silicon nitride over conductively-doped polycrystalline silicon to form an insulative material over the polycrystalline silicon, and to simultaneously deposit the silicon nitride over borophosphosilicate glass (BPSG) to form a barrier layer over the BPSG.
A difficulty that can occur during such simultaneous deposition of silicon nitride is that the silicon nitride can form much more rapidly over the polycrystalline silicon than over the BPSG. Specifically, a nucleation rate of silicon nitride on silicon is typically significantly higher than it is on silicon oxides. Accordingly, the silicon nitride thickness over the polycrystalline silicon will be much thicker than that over the silicon oxide. For instance, a 50 xc3x85 thick silicon nitride layer can be formed on hemispherical grain polysilicon in about the time that it takes to grow a 20 xc3x85 thick silicon nitride layer on BPSG. The 20 xc3x85 thick silicon nitride layer may not be sufficient to be a suitable barrier layer to subsequent penetration of undesirable materials through the silicon nitride and into the BPSG. If materials penetrate into the BPSG, they can subsequently penetrate through the BPSG and to an underlying active region, which can ultimately cause failure of devices formed relative to the active region.
One solution to the above-described difficulty is to grow a thicker layer of silicon nitride on the polycrystalline silicon to enable a sufficiently thick barrier layer to be formed on the BPSG. However, such can result in too thick of a silicon nitride layer being deposited on the polycrystalline silicon for later use as a dielectric material in a capacitor device. It would be desirable to develop methodology whereby silicon nitride can be simultaneously deposited over a silicon oxide and a conductively-doped silicon material, with the deposition rate being substantially the same over both the silicon oxide-containing material and the conductively-doped silicon material.
In one aspect, the invention encompasses a method of forming a nitrogen-containing mass. A substrate is provided, and the substrate comprises a silicon-containing mass and a silicon oxide-containing mass. The silicon-containing mass has substantially no oxygen therein. A first nitrogen-containing mass is formed to be across the silicon oxide-containing mass and not across the silicon-containing mass. After the first nitrogen-containing mass is formed, a second nitrogen-containing mass is formed to extend across the silicon-containing mass and across the silicon oxide-containing mass, with the second nitrogen-containing mass being over the first nitrogen-containing mass.
In another aspect, the invention encompasses a method of forming a silicon nitride layer. A substrate is provided which comprises a first mass and a second mass. The first mass comprises silicon and the second mass comprises silicon oxide. A sacrificial layer is formed over the first mass. While the sacrificial layer is over the first mass, a nitrogen-containing material is formed across the second mass. After the nitrogen-containing material is formed, the sacrificial layer is removed. Subsequently, a silicon nitride layer is formed to extend across the first and second masses, with the silicon nitride layer being over the nitrogen-containing material. Also, a conductivity-enhancing dopant is provided within the first mass.
In yet another aspect, the invention pertains to methods of forming capacitor constructions.